1. Field of the Invention
The present invention relates to the field of pipe connections. More particularly, the present invention relates to the field of welded pipe connections normally useful in oil and gas production, refining and transportation industries.
2. Background of the Related Art
Corrosion barriers are useful in conjunction with pipes by joining pipes whose interior regions are coated with protective materials, such as thin polymer based coatings or cement based liners, which form a protective barrier between the pipe material and the materials passing through the pipe. In some instances, such as in highly corrosive environments, the protective barrier may be constructed of a tubular PTFE liner or other polymer based material.
In the oil and gas transportation industry, the most common method of connecting individual lengths of pipe is by welding the ends together. Welding of the pipe ends presents several pipe material protection problems. The Cylindrical Corrosion Barrier For Pipe Connections, U.S. Pat. Nos. 5,547,228 and 5,566,984 provide for methods of solving those pipe material protection problems and are incorporated by reference herein.
Another problem arises in pipe welds when a section of pipe is being repaired, replaced or otherwise joined to another section of pipe and residual gases, fluids or vapors may be present in the pipe section adjacent the work site. These residual fluids or vapors often present a hazardous situation for welding two pipe sections together and have been isolated from the welding site in a number of ways, such as inserting a large rubber plug into the exposed ends of the pipe. However, the plug is typically not removable and, when the pipe is put back into service, may become lodged or otherwise form a restriction or trash buildup in the pipe.
Yet another problem arises in repairing, replacing or otherwise joining a pipe section to another pipe section, when the pipe section must be continuously lined even across the area of the pipe weld. This problem is inherent with rigid pipe and rigid linings that must be fabricated to an exact length in order to be positioned and welded between two fixed ends of pipe, such as the two pipe ends exposed when a worn section of pipe is cut out and replaced. Particularly over short distances, a new pipe section having a nearly exact length and a liner having sufficient length to extend beyond the ends of the new pipe section, across the weld area and into communication with a liner or coating in the adjacent two pipe ends, can not be physically manipulated into positioned.
Therefore, there is a need for a lined or coated pipe section that can be welded between two ends of an existing lined or coated pipeline and provide a continuous protection barrier in the pipe, even across the area of the weld. It would be desirable if the lined or coated pipe section could be installed even between pipe ends spaced at very short distances. It would be further desirable if the lined or coated pipe section were designed to avoid being damaged during welding of the pipe section into the pipe line. Preferably, the lined or coated pipe section would be of equal or greater physical strength than the rest of the pipeline. Optionally, it would be desirable if the lined or coated pipe section could be used to isolate hazardous gases, fluids or vapors from the site of the weld.
The present invention provides an adjustable pipe connector which provides a connection between the ends of adjacent sections of pipe where hazardous, corrosive or flammable gases, fluids or slurries flow therethrough. In one embodiment of the invention, the connector is particularly useful for joining pipe ends that are coated and/or contain corrosion barriers like the one described in U.S. Pat. No. 5,566,984. When two pipe ends are provided with corrosion barriers, it may be difficult if not impossible to place a standard connector between the pipe ends without damaging the corrosion barrier. Therefore, the present pipe connector has multiple telescoping sleeves that provide intimate contact with the pipe ends and can be adjusted in length to accommodate the two pipe ends each with a corrosion barrier positioned therein
One embodiment of the pipe connector has a first sleeve with a generally cylindrical inner surface; a second sleeve positioned inside the first cylindrical sleeve; a third sleeve positioned inside the second cylindrical sleeve, and a fourth sleeve positioned inside the third cylindrical sleeve, such that the first, second, third, and fourth sleeves are coaxially aligned with one another. Preferably, the generally cylindrical inside surface of the first sleeve defines an annular shoulder facing the first end of the first sleeve and a minor diameter portion extending from the annular shoulder toward the first end. The inner surface of the first sleeve near the first end contacts the outer surface of the third sleeve in a telescoping relationship. The second sleeve has first and second ends and the outer surface of the second sleeve contacts the inner surface of the first sleeve adjacent to the minor diameter portion. The inside surface of the second sleeve contacts the outer surface of the third sleeve near the first end and the outside surface of the fourth sleeve near the second end.
Preferably, the third sleeve has first and second ends and the inside surface near the first end contacts the outside surface of the fourth sleeve. The fourth sleeve has first and second ends and the generally cylindrical outer surface preferably defines an annular shoulder facing the first end and a minor diameter portion extending from the annular shoulder toward the first end.
In another embodiment, there is provided a pipe plug useful for joining coated and uncoated pipes that have once had flammable or caustic vapors or fluids flowing therethrough. The pipe plug provides a temporary protective barrier that is easily broken and displaced once the pipe section is fully installed and put back into service. The pipe plug has a cylindrical sleeve having an outer surface, an inner surface, a first and second end; a barrier extending over the first end of the cylindrical sleeve. The barrier is temporary and acts to contain vapors and/or gases that may be present in the pipe. The outer surface of the first end of the sleeve sealingly engages the inside surface of a pipe end to hold the plug and barrier in place while the pipe is being repaired.
The outer surface of the plug preferably has at least one circumferentially extending recess and a sealing element positioned within the recess. A barrier ring may be positioned around the barrier to hold the barrier over the first end of the sleeve. An additional circumferential recess disposed in the outer surface of the cylindrical sleeve has a metal ring disposed therein for completing a weld to another pipe end if necessary.
Another embodiment of the present invention provides a pipe connector having an extendable pipe structure with a middle, first and second pipe ends. The extendable pipe structure has an inner cylindrical surface of a diameter that is substantially the same as the inner diameter of the pipe and first and second concentric pipe sleeves extending from the first and second pipe ends toward the middle. The concentric pipe sleeves are engaged in a telescopic relationship.
There is an extendable pipe liner with a middle, first and second liner ends having an outer cylindrical surface of a diameter that is substantially the same as the inner diameter of the pipe to be connected, and first and second concentric liner sleeves extending from the first and second liner ends toward the middle. The concentric liner sleeves are also engaged in a sealed telescopic relationship.
The first and second liner ends are coupled to the first and second pipe ends and extend beyond the first and second pipe ends. The portion of the first and second liner ends extending beyond the first and second pipe ends has one or more sealing members disposed in the outer cylindrical surface thereof for sealing against the inner surface of the pipe. The first and second liner sleeves are supported by the first and second pipe sleeves.
Preferably, the inner surface of the first concentric sleeve forms an annular shoulder in one end of the pipe structure facing the middle of the pipe structure and contacts an outer surface of the second concentric sleeve. The first concentric liner sleeve may also have an inner surface that forms an annular shoulder in one end of the liner facing the middle of the pipe liner, where the inner surface of the first concentric sleeve sealingly contacts the outer surface of the second concentric liner sleeve. This construction is useful in that the connector can be retracted so that the sleeves rest on top of one another reducing the unit to a manageable size and extended to a desired length at the point where a connection will be made.
At least one circumferential recess may be disposed in the outer surface of the first liner end and the recess may have a metal ring disposed therein to use in welding the pipe to the pipe connector while insulating the interior of the pipe from the heat generated by the weld.